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Journal Scan: Vaccines and other injections and the development of injection-site sarcomas in cats

Using client questionnaires to obtain histories of vaccine and other injections, researchers prospectively evaluated 436 feline masses: 181 soft tissue sarcomas, 96 tumors at nonvaccine sites (control group 1), and 159 basal cell tumors (control group 2). A third control group was formed by combining control groups 1 and 2.

What they found

A history of intrascapular administration of long-acting corticosteroid injections was associated more often in cats with sarcomas than in the controls. Among the 56% of cats with sarcomas that had received vaccines in that area, there was no difference in risk between inactivated and modified-live vaccines. Cats with sarcomas in the rear limb region were more likely to have received inactivated vs. recombinant vaccines, but neither vaccine was found to be risk-free.

Take-home message

Recombinant vaccines may be less likely to induce sarcoma formation, but no vaccine was found to be risk-free. Injections of long-acting corticosteroids were also associated with sarcoma formation.